THE IPv4 + IPv6 SUBNET WORKBENCH
Turn an IP and prefix into exact address bounds, readable bit patterns, and aligned child networks.
START WITH A PREFIX
Local Math / No Network Lookup
Use one IPv4 or IPv6 address followed by a numeric prefix: /0–/32 for IPv4, /0–/128 for IPv6. A host address is accepted; the result shows its containing network.
Do not enter a hostname, dotted mask, port, IPv6 zone identifier, or bracketed address. Splitting needs enough remaining host bits.
READ THE ADDRESS SPACE
NORMALIZED NETWORK / IPv4
Entered address 216.73.216.68 belongs to the network above. Host bits were cleared to find its start.
Lime marks the network portion; outlined cells mark host bits. These are the entered address’s bits, not the mask.
Conventional IPv4 host counts exclude the network and directed broadcast addresses. Special-purpose ranges and assignment policy can further restrict use.
The reverse name is calculated, not looked up. No PTR, DNS, registration, or reachability request is made.
Initial result: connection IP with an illustrative prefix. Nothing was detected or changed on your network.
READ THE OUTPUT WITH CONTEXT
The first boundary identifies the block. The calculator cannot know which host your router uses.
Reservations, gateways, infrastructure, and provider rules reduce the pool you can actually assign.
An address classification is not a security verdict. Routing, access controls, and the actual environment still matter.
TERMINAL FRIENDLY
Only your source IP and a newline—no banner, markup, or extra fields.
curl ipcalculator.infoThe bare command uses HTTP. Use https://ipcalculator.info for encryption. This endpoint reports an IP, not its subnet mask.
FROM THE PREFIX TO THE PLAN
Follow the network boundary, mask, wildcard, and exact address range.
4 min read02 / IPv6Understand IPv6 bounds, address notation, and why assignment rules matter.
4 min read03 / IN THE FIELDWork through child blocks, capacity, and checks before deployment.
5 min read